Toxoplasma may predate cats

New findings by Murdoch University’s Parasitology research group indicate the domestic cat may be off the hook for introducing the Toxoplasmosis disease to Australia.

Professor Andrew Thompson, Chair of Parasitology at Murdoch, said recent field studies have shown the disease is far more common than anticipated.

“We’ve seen some native animal populations where up to 80 per cent were affected by Toxoplasmosis, but all were healthy animals with no clinical diseases,” Professor Thompson said.

“This raises the interesting question of how the disease is so prevalent because there are not enough cats in Australia to account for such a high level of disease in native wildlife.”

Until now, cats were thought to be responsible for the introduction of Toxoplasmosis into Australia, however the new findings indicate there may have been an Australian carnivore that was helping spread the disease before the cat’s arrival.

“We know the cat is highly important to the spreading of Toxoplasma because it’s able to contaminate the environment, which it does through its faeces and its coat,” Professor Thompson said.

“It’s currently the only known animal to do that, but following our research we may need to look more closely at some of the native carnivores.”

Professor Thompson said most infections were a result of handling or eating poorly cooked meat, as Toxoplasmosis resides in warm-blooded animal and bird tissues.

“Toxoplasma is susceptible to a healthy immune system, so healthy people or animals that are affected will quickly suppress the disease, and it will reside, dormant, in the tissues of the host – possibly for the rest of their life,” he said.

“This is why it’s considered a ‘common infection but rare disease’.”

Working in collaboration with Michael Grigg from the National Institute of Health of the United States, Murdoch University’s two postgraduate students, Nevi Parameswaran and Shuting Pan, will continue to investigate the occurrence and genetic diversity of Toxoplasma in Australia’s native mammals, alongside the expertise of Murdoch University’s Associate Professor Alan Lymbery and Dr Andy Smith.

The collaboration is part of an Australian Research Council and Department of Environment and Conservation project.

Image - Toxoplasma in blood, courtesy of Dr Andy Smith.